Colfer Asked To Write Sixth HHGTTG Book
clickety6 writes "Eoin Colfer, the Irish author of a number of books (including the popular children's book series 'Artemis Fowl'), has been directly approached by Douglas Adam's widow, Jane Belson, to write a sixth book to continue the (even more) increasingly inaccurately named Hitchhiker's Guide to the Galaxy trilogy."
Douglas Adams himself mentioned that Mostly Harmless was too dark and wanted the series to finish on a more upbeat note (http://en.wikipedia.org/wiki/Mostly_Harmless#Adams_on_Mostly_Harmless ). So it is quite plausible to believe that his widow would want to make her husband's wish true.